Guidewire extension system with tactile connection indication

ABSTRACT

A guidewire extension system including a guidewire and an extension wire is disclosed. The system includes female and male connector segments located on the proximal end of the guidewire or the distal end of the extension wire. The hollow female connector segment, in one embodiment, includes a radial lip which intersects with at least one, i.e., one or more, lateral slots. The male connector segment includes an external groove. When the male connector is inserted into the female connector segment, the slots are expanded and the lip snaps into the groove providing a tactile indication that connection is completed. 
     No restriction or frictional fit is created. The guidewire and extension wire are freely rotatable with respect to each other and can be multiply connected and disconnected. 
     Methods of catheter exchange with tactile indication of guidewire extension wire connection are disclosed.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of application Ser. No.08/220,902 filed Mar. 31, 1994, now U.S. Pat. No. 5,546,958.

FIELD OF THE INVENTION

The present invention relates in general to the field of guidewires.Guidewires are used to position catheters in exploratory procedures,diagnosis, and treatment of various medical conditions. Moreparticularly, this invention relates to a guidewire extension system forconnecting or coupling a guidewire, primary or initial wire to anextension or secondary wire during a medical procedure.

BACKGROUND OF THE INVENTION

Guidewires are used in various medical procedures to position medicaldevices at desired locations within a patient's vascular system.Guidewires, which are steerable, are inserted and maneuvered through thepatient's vasculature to a previously chosen location. Once in place,the guidewire provides the means to place a non-steerable device, suchas an over-the-wire catheter, at the chosen vascular site. For example,a catheter is slid over the guidewire until the catheter, or someworking portion thereof, is positioned within the vasculature at thedesired location. Generally speaking, guidewires of a standard lengthare longer than the non-steerable devices with which they are used topermit independent movement of the device and the wire.

Angioplasty is one interventional procedure where a guidewire is oftenused. In angioplasty a dilatation catheter having an inflatable balloonstructure is used to compress occlusive or blockage material against thesides of a vessel, thereby permitting (ideally) circulation to bereestablished. In preparatory procedures, the site of a vascularrestriction, occlusion or stenosis is identified. In the usualprocedure, the guidewire is inserted into the patient's femoral arteryand maneuvered or steered to the location of the restriction.Maneuvering of the guidewire is facilitated by a video X-ray devicewhich allows the physician to observe the movement of the guidewire'sdistal tip. The guidewire distal tip generally comprises a radiopaquemetal to enhance X-ray viewing. A dilatation catheter then is insertedover the guidewire so that its working segment is located adjacent therestriction. Generally this means that the catheter balloon ispositioned adjacent the vascular restriction or blockage.

During a simple angioplasty procedure, the dilatation catheter balloonis inflated to open the restriction, and then is removed along with theguidewire. However, complications sometimes arise which prevent thephysician from completing this simple procedure. Occasionally theballoon catheter malfunctions. Sometimes a larger (or smaller) balloonis required further to dilate the vascular restriction, or anotherdevice or other type of catheter is needed to remove vascular material.For whatever the reason, the guidewire extension system of thisinvention is used when the catheter, or other such device, has to beremoved and replaced with another device or catheter.

In the usual procedure to exchange catheters, the guidewire is removedfrom the patient, leaving the catheter in the vascular system. Anexchange wire is inserted through the catheter and the catheter removed,leaving the exchange wire in place. The new catheter is inserted overthe exchange wire and the exchange wire removed and replaced with theguidewire.

It is desirable to keep the guidewire in the patient's vasculature forvarious reasons. One reason is that the initial placement of theguidewire requires extensive, time consuming, manipulation. Removal andrepositioning of the guidewire would be equally time consuming, possiblyrequiring a patient to be exposed to additional drugs, radiation, and,in general, additional trauma. It is also of importance that once theguidewire has been steered to a position across a lesion, that thecrossed lesion position not be lost by removal of the guidewire.Guidewires removed from a crossed lesion may induce spontaneous vascularrestriction or closure making repositioning of the guidewire difficultif not precluded.

In those cases where catheter exchange is desired, the physician wouldsimply prefer to remove the catheter over the guidewire, leaving theguidewire positioned in the patient. However, to permit catheterexchange, a guidewire over which a catheter is to be exchanged must besufficiently long to allow the physician to grip a portion of the wireas the catheter is being withdrawn over the guidewire. This requires theguidewire to be long enough to provide an external portion longer thanthe catheter in addition to the guidewire portion remaining in thepatient.

Unfortunately, a guidewire of sufficient length to provide suitably longexternal and internal portions has inferior handling characteristics,thereby making more difficult the steering and maneuvering manipulationsneeded for guidewire placement. The added length also imposes itself onthe usually cramped vascular suite thereby causing distractions fromother support activities. It is for these reasons that guidewires areusually only slightly longer than balloon catheters, e.g., 20-50centimeters longer, and that a much longer exchange wire is used onlywith exchange procedures.

Illustrating the above, a dilatation catheter has a shaft length in therange of about 120 cm to about 150 cm, a suitable guidewire for such acatheter would have a length in the range of about 150 cm to about 180cm and an exchange wire would have a length in the range of about 260 cmto about 300 cm. As can be imagined from the above, utilization of anexchange wire in an exchange wire procedure is complicated and timeconsuming. This invention simplifies catheter exchange and eliminatesthe need to use an exchange wire.

A recent development involves coupling or connecting a second length ofwire, sometimes called an extension wire or secondary wire, to theexposed, proximal end of a positioned guidewire. The secondary wirelength should be sufficient to allow the catheter to be withdrawn whileleaving the primary or lesion-crossing guidewire positioned within thepatient's coronary or peripheral vasculature. Various approaches havebeen suggested for effecting the attachment of an extension wire to aguidewire.

In one approach, such as that described in U.S. Pat. No. 4,922,923 toGambale et al., a guide wire and an extension are joined together bycrimping. A special crimping tool is disclosed in the Gambale et al.,'923 patent. A drawback of this approach is that once the wires havebeen crimped, the connection therebetween is substantially permanent,and the extension wire cannot be detached from the guidewire except bysevering it, e.g., by cutting.

Instead of crimping the guidewire to the extension wire, attempts havebeen made to engage the extension wire to the guidewire frictionally.Such attempts are described, for example, in U.S. Pat No. 5,113,872 toJahrmarkt et al., and related U.S. Pat No. 5,117,838 to Palmer et al.These two patents disclose a guidewire extension system in which thedistal end of the extension wire comprises a small diameter tube inwhich there is disposed a small diameter, open pitch, flat wire coiledspring. The proximal end of the guidewire has a reduced diameter portionwhich is inserted into the tube assembly to complete the connection. Thereduced diameter proximal end of the guidewire is slightly larger thanthe internal diameter of the coiled spring of the extension wire,thereby creating a frictional engagement when one is inserted into theother. Palmer et al. disclose the utilization of a swivel joint forminimizing twisting of the extension guidewire when connecting ordisconnecting it from the extension wire. A device as described in thesetwo patents would be very difficult to manufacture reliably andapparently requires an alignment tool to ease insertion.

U.S. Pat No. 4,875,489 to Messner et al., discloses an extendableguidewire in which concentric tubular segments are secured to one or theother of the sections to be connected. The inner tubular segment has alongitudinal slot therein which permits it to expand when a cooperatingmale portion is inserted therein. The outer tubular member of theconnector assembly restricts the expansion of the inner tubular memberas the male portion is inserted therein.

U.S. Pat. No. 4,846,193 to Tremulis et al., disclose a guidewire havingfirst and second telescopically extendable sections movable betweenaxially extended and retracted positions. No disengagement of theguidewire and extension wire is disclosed.

U.S. Pat. No. 4,966,136 to Kraus et al., discloses an internallythreaded female connection member secured to the distal end of theextension wire. The internally threaded female connection member isdisclosed to be freely rotatable with respect to the extension wire withsecurement thereto by means of a collar. The body of the extension wirehas a distal enlargement which cooperates with the collar to permit itto be freely rotated. The female connection member of the extension wirecooperates with a threaded male portion located on the proximal end ofthe guidewire. The mechanism disclosed by Kraus et al., requires thedifficult step of threading the segments into each other. Threadingpieces having the diameters of a guidewire and an extension wire intoeach other can be difficult to accomplish, especially under operatingroom conditions.

U.S. Pat. No. 4,827,941 to Taylor et al. discloses a guidewire extensionsystem employing a tubular female connector portion on one wire and acooperating male portion on the other. The connecting male portion hasan effective diameter in one radial dimension which is slightly largerthan the inner diameter of the tubular portion. In a preferred practice,the male end portion of the Taylor et al. guidewire has an undulatingshape, which, when inserted into the tube creates an interferencefriction fit.

U.S. Pat. No. 5,247,942 to Prather et al. discloses a guidewire with aswivel. The Prather et al. invention provides for permanent connectionof a main part and an extension part. A swivel is included in the systemto permit the permanently affixed parts to be rotated with respect toeach other to enhance steerability of the main or guidewire segment. ThePrather '942 structure has the same drawback as the Gambale '923 systemdiscussed above.

U.S. Pat. No. 5,246,009 to Adams discloses a complicated guidewireassembly utilizing an inner core wire and an outer tube. Torquetransmission is an aspect of the Adams invention.

U.S. Pat. No. 5,271,415 to Foerster et al. describes a guidewireextension system comprising a tubular outer body with guidewire andextension wire elements, e.g., helically wound wires, therein. Thedevice of Foerster et al. has the same disadvantage as that of the Krauset al. '136 patent, i.e., the interconnect step requires threading ofthe parts into each other. Moreover, the device described by Foerster etal., with brazed wires inside a tubular structure, may be difficult tomanufacture.

The guidewire extension systems discussed above all have one or moredrawbacks. Some are difficult or tedious or intricate to engage anddisengage. Others do not disengage at all. While frictional engagementovercomes the disadvantages of crimping, disengagement may occur tooeasily. Problems of discontinuity at the guidewire/extension wireconnection, e.g., kinking, have been experienced with some systems. Someconnector systems are difficult or expensive to build, especially insmaller diameter sizes. Moreover, prior extendable wires for use incoronary angioplasty procedures have been found to be unsuitable inperipheral arteries because the connections are not sufficiently strong.Further, some connections have larger diameters than the rest of theguidewire system. This may cause snagging of, e.g., over-the-wirecatheters. It also means that the catheter with which such connectionsystem is used must have a larger internal diameter lumen than would benecessary were a smaller diameter coupler employed.

Accordingly, a principal object of the present invention is to provide aguidewire extension system which is reliable, easy to use, and easy tomanufacture, particularly in smaller diameter, coronary sizes.

Another object of the present invention is to provide a guidewireextension system which does not require that either the guidewire orextension wire be rotated when attaching one to the other, i.e., theycan be non-rotatively coupled. It is advantageous that the guidewire beheld stationary because the guidewire is located within the patient'sblood vessel where unnecessary movement can induce trauma. It is alsoadvantageous to have the majority of the length of the extension wireheld stationary (e.g., by retention within a carrier structure) duringthe connection process. Having the extension wire self-contained in atubular carrier package allows medical personnel to concentrate uponengaging the two wires using the present extension system. Anuncontained extension wire is awkward, and thus complicates the processof effecting a guidewire/extension wire union during a medicalprocedure.

It is a further object of this invention to provide an easily attachable(and reattachable) and easily detachable guidewire extension systemwhich has a readily identifiable tactile sensation, e.g., a “snap”, whenthe system components are affirmatively attached, engaged, or coupled.

It is still a further object of the present invention to provide aguidewire extension system which has substantially the same flexibilityand pushability at its connection as that of the remainder of the lengthof the guidewire. The system provides an advantageously controllablecoaxial alignment of the guidewire and extension wire.

It is yet another object of the present invention to provide a unitizedguidewire extension system having a substantially uniform, smooth,continuous outer diameter or profile along the guidewire, connector, andextension wire. A smooth, continuous transition in external profile fromthe distal end of the guidewire to the proximal end of the extensionwire, especially over the connector segment, permits an over-the-wirecatheter to be positioned by use of the guidewire/extension wire withoutgetting caught. Methods of manufacturing an extension system of thisinvention and methods of using a system of this invention also aredisclosed.

BRIEF SUMMARY OF THE INVENTION

Briefly, in one aspect, the present invention is an extension system foraffirmatively connecting the proximal end of a guidewire to the distalend of an extension wire. In its connected form, the entire structure issometimes referred to herein as an exchange wire. In one practice, atactile “snap” is experienced by the user when guidewire/extension wireconnection or docking is achieved.

In accordance with one aspect of the present invention, there isprovided a coupler for a guidewire/extension wire system, the couplercomprising a male segment and a cooperating female segment. The couplerof this invention permits multiple coupling and decoupling, as needed,of the guidewire/extension wire to which it is attached. The male andfemale segments are fixedly attached to one or the other of the distalend of the extension wire or the proximal end of the guidewire, and yetthe system permits either or both of the guidewire/extension wires to befreely rotated with respect to each other without the structuralcomplication of, e.g., a separate swivel.

The female coupler segment of this invention comprises a hollow,elongate sleeve, the sleeve having opposite ends and a sleeve wall whichdefines inside and outside sleeve diameters, one of said sleeve endshaving an inside diameter such that it can be firmly attached to one ofsaid guidewire or said extension wire. The sleeve wall has an interiorreduced diameter zone, segment, bead or lip located (in a preferredpractice) approximately midway between the opposite ends of the sleeve.Passing through the reduced diameter zone is at least one, i.e., one ormore axial or lateral slots or slits. The slot(s) or slit(s) of thisinvention pass entirely through the sleeve wall. In a preferred practiceof this invention, the aforementioned female coupler segment reduceddiameter zone is created by roll-forming a segment of formable hypotube,i.e., by rolling a bead or dent into the sidewall of a segment ofhypotube. In one practice of this invention, a plurality of axial slotspass through the reduced diameter zone. In a further preferred practice,a single axial slot passes through the reduced diameter zone or bead,generally perpendicular to its plane or diameter.

The male coupler segment of this invention comprises an elongate memberlocated on the other of the guidewire or extension wire. The elongatemember has an exterior surface and opposite ends which are referred toherein, as insertion or leading and following or connection ends,respectively. The insertion or leading end of the elongate member is thefirst portion of the elongate member to enter the female sleeve in thecoupling process. The male coupler segment is affixed to the proximalend of the guidewire or the distal end of the extension wire, asappropriate. Several attachment locations and methods of attachment arediscussed below. The exterior surface of the elongate member defines atleast a portion of a radial groove and an annular shoulder in thefollowing end, the groove having a diameter which cooperates with thefemale coupler segment bead so that when said male member is insertedinto said female segment, the bead passes or slides along the exteriorsurface of the male member in a slightly separated position, passes oversaid shoulder and returns to a non-separated position within the grooveor notch. In this manner, the female coupler segment is retainedsubstantially coaxially along the male coupler segment after insertion.Coupling occurs with a tactile sensation that insertion is completed,e.g., with an identifiable “snap.”

In a further practice, the outside diameter of the male coupler segment,as defined by its exterior surface, is less than the inside diameter ofthe female coupler sleeve, leaving an annular space therebetween andprecluding a possible restriction or frictional interaction between thecooperating segments.

In yet a further preferred practice, the male member has a taperedinsertion end, permitting easy insertion of said male member into thefemale coupler sleeve.

A guidewire extension system of this invention can be used to connect anotherwise conventional extension wire to a steerable guidewire having aplurality of multifilar, oppositely wound coils. Of course the guidewirealso may have only a single coil, depending upon application. Forsmaller diameter guidewire applications, e.g., 0.014 in. diametercoronary wires, a guidewire core having no coil at all may be used.

In another practice, the female segment is disposed on the distal end ofthe extension wire and the male segment is disposed on the proximal endof the guidewire.

BRIEF DESCRIPTION OF THE FIGURES

The present invention may be better understood with reference to thedetailed description below and the attached FIGURES wherein likereference numerals designate like features throughout, and wherein:

FIG. 1 is a perspective view of an embodiment of the present invention;

FIG. 2 is a cross-sectional view of the embodiment of the invention ofFIG. 1 after the connector segments have been mated;

FIG. 3 is a sectional view of a female connector segment of thisinvention;

FIG. 3A is an end view of the segment shown in FIG. 3;

FIG. 4 is a sectional view showing the structure of an attachmentbetween a female coupler segment of this invention and the extensionwire to which it is attached;

FIG. 5 is a partial sectional view of a male coupler segment of thisinvention;

FIGS. 6, 7, 8, 9 and 11 are partial sectional views of furtherembodiments of male coupler segments of this invention;

FIG. 10 is a side view of a male coupler segment of this invention.

FIG. 12 is a sectional view of an alternative female coupler sleeve ofthe present invention.

FIG. 13 is a perspective view of a further embodiment of the invention.

FIG. 14 is a sectional view of the invention of FIG. 13 after itscomponents have been connected.

DETAILED DESCRIPTION OF THE INVENTION

One of the advantages of this invention is that the male member and thefemale coupler are conveniently coupled and decoupled using insertionand withdrawal forces easily applied by medical personnel. They are notpermanently affixed to each other and no restriction or frictional fitis created. Neither of the male nor the female coupler segments arethreaded, thereby eliminating the need to create those threads. Thisalso eliminates any need to thread relatively small components into eachother during a coupling/decoupling sequence. In application of thisinvention, no rotation of either part is required in order to achievecoupling and decoupling.

The extent of coaxial alignment at the coupler can be controlled byadjusting the length of the overlap between the male coupler segment andthe female coupler segment. For example, if a relatively longer malecoupler segment is used, i.e., an elongate member which is relativelylonger between its leading end and its groove, then axial alignment ofthe connected ends of the guidewire/extension wire is more rigidlymaintained. Conversely, if a shorter male member (up to and including asubstantially spherical ball) and a corresponding sized female couplersegment are used, then the axial rigidity of the overlapped couplersegments will be relatively minimal. Adjustment of guidewire/extensionwire overlap at the coupler may produce changes in the “feel” of anextended guidewire to a catheter user.

One skilled in this art will appreciate that there are likely to be anumber of structural equivalents to the “lip” and “groove” constructiondescribed here. All of such constructions are within the scope of thepresent invention. For example, instead of a lip on the female couplersegment, one or more dimples or protrusions (or a series or locus ofdimples or protrusions) could be machined, stamped, or molded therein.In that embodiment, the male segment would have surfaces, detents, ordents which would cooperate with the dimples to provide a tactilesensation at coupling and to couple the segments. A slide-stop (such asthat mentioned in U.S. Pat. No. 5,247,942) could be used if thecooperating surfaces of the slide and stop permitted the slide/stop tobe decoupled using decoupling or withdrawal forces in the rangediscussed below.

It will also be appreciated that a “lip” or bead, as that term is usedherein, may be located within the coupler sleeve rather than at one end.In such an arrangement, an intermediate narrow region or lesser diametersegment would be stretched, expanded or moved further within the couplersleeve to create the tactile sensation of connection as the male memberpassed therewithin. One or more lateral slots would be utilized and passthrough the intermediate narrow region to permit the male member to passtherethrough more easily. As noted above, a preferred practice of thisinvention is utilization of a single axial slot passing through thebead. The single slot embodiment is particularly preferred for smallerdiameter coronary guidewire applications, e.g., guidewire applicationswhere outside diameters in the range of about 0.010 inches to about0.020 inches, preferably about 0.014 inches to about 0.018 inches areused.

As is shown in FIG. 1, a guidewire extension system 10 embodyingfeatures of the present invention has a guidewire or main section 11which is adapted to be inserted into a patient's vascular system and anextension wire or extension section 12 which can be connected anddisconnected to the main section 11. Connection and disconnection ofguidewire 11 and extension wire 12 facilitates catheter exchange withoutthe need for removing the main guidewire section 11 from the patient'svascular system. In the embodiment shown, guidewire section 11 generallycomprises an elongated shaft 13 having a distal end (not shown inFIG. 1) with a male coupler segment 15 located at its proximal end. (Thedetails of a preferred guidewire structure are discussed below.) Shaft13 optionally may be covered with a polymeric, e.g.,polytetrafluoroethylene (PTFE), polyurethane, or other coating (notshown). Single filar coils, multifilar coils, radiopacity markers, orother commonly utilized guidewire structures, may be disposed on shaft13. These structures have been omitted from this description of theinvention for purposes of clarity.

Extension section 12 has an elongated shaft 24 with a hollow femalecoupler segment 26 secured to its distal end. Female coupler segment 26may be fixed to extension wire 24 using techniques well known in thisart such as resistance welding, crimping, gluing, soldering, or brazing.Female coupler segment 26 may comprise, for example, a suitably modifiedsection of hypotube brazed to the distal end of an extension wire.Female coupler segment 26 may also be machined from a segment of solid,cylindrical core workpiece. Powder metallurgy techniques also may beused to manufacture female coupler segment 26.

Also shown in FIG. 1 are the plurality of longitudinal slots 25 and acircular lip 16. Slots 25 intersect and divide circular lip 16 producingopposite, semicircular tabs 17, 18 which can be radially separated (inthe direction of arrows 19) as male and female segments 15 and 26 aremated. Slots 25 may be machined into coupler segment 26 usingconventional grinding and cutting operations or they may be created byany of a number of other known processing techniques includingelectrical discharge machining. The portion of the shaft 24 proximal tothe female member 26 may be covered with, e.g., a polymeric, or othertype of coating.

Male connector segment 15 is elongate, having opposite leading orinsertion and following ends 20, 21 respectively. In this embodiment,insertion end 20 is tapered (at 22) to ease the connection process. Theexterior surface of male connector segment 15 further defines a radialgroove 23.

FIG. 2 illustrates the detailed interaction between lip 16 and radialgroove 23. FIG. 2 is a cross-sectional view of an embodiment of theinvention 10, shown in FIG. 1, after the segments have been coupled or“snapped” together. In this embodiment, female coupler segment 26comprises a section of hypotube which has been brazed (at 40) toextension section wire 12. Other methods of securement, e.g., soldering,or gluing, may be employed. As is shown, the glue, solder, or braze zoneitself can be employed to provide a smooth transition between theguidewire or extension wire to which the female coupler segment isattached and to the coupler segment itself.

A circular lip 16 of this invention is described in greater detail asfollows. Circular lip 16 has a slightly rounded or tapered leading oropening edge 42, a substantially uniform or single diameter intermediateportion 44 and an angled or rounded interior edge or shoulder 46 whichmerges (at 50) to the interior diameter 48 of the hypotube section 26.Angled interior edge 46 can be, for example, the byproduct of drillingto create interior diameter 48. Interior edge 46, in cooperation withthe configuration of radial groove 23, determines at least the magnitudeof the force needed to disengage male and female coupler segments 15 and26. Other factors such as the material employed, its treatment prior toincorporation into the present coupler, and the precise interactionbetween the slots and tabs also affect the magnitude of withdrawalforces.

The details of male coupler segment 15 also are shown in FIG. 2. Malecoupler segment 15 (best seen in FIG. 1) is defined by the configurationof exterior surface 60 of the male segment of the connector system. Aswas discussed above, male segment 15 has an insertion end 20 and afollowing end 21. Insertion end 20, in this embodiment, is rounded ortapered (at 22) to provide ease of insertion. The outside diameter 62 ofthe male segment 15 leads to and defines radial groove 23. Radial groove23, in this embodiment, comprises an angled, radiussed, or perpendicularannular shoulder 23A, a neck 23B which has a uniform diameter, and aradial stop surface 23C. Radial stop surface 23C can be disposedsubstantially perpendicularly to the axis of the guidewire extensionwire system, as is illustrated, or it may be filleted or shaped toprovide a more rounded stop. As shown, interior edge 46 of femalecoupler segment 26 is angled so as to be complimentary with and tocooperate with annular shoulder 23A when lip 16 is lying within radialgroove 23. Radial stop surface 23C normally controls the extent to whichthe male and female coupler segments can be engaged, provided theelongate member is short enough to fit completely within female couplersegment 26 and not abut against the extension wire main section. Forpurposes of orientation, longitudinal slot 25 is shown in phantom.

Three significant observations should be made with respect to theembodiment of FIG. 2. First, the interior diameter 48 of female couplersegment 26 is larger than the outside diameter 62 of male coupler 15.This fact means that no restriction or frictional fit is needed forcoupling to occur between the male and female segments. The absence of arestriction fit also permits male and female coupler segments 15, 26(and therefore the guidewire or extension wire to which they areattached) to rotate freely with respect to each other. In other words,this embodiment of the invention obviates the need for a structure likethe swivel of U.S. Pat. No. 5,117,838(Palmer et al.) described above.

The second important observation is that the structure shown in FIG. 2provides a definite tactile “snap” when the segments are coupled. Asound may also be heard, especially in the larger sized peripheralwires. Whether a sound is generated or not, the tactile sensation ofcoupler engagement is a significant indicator to the system user thatcoupling is complete. A small amount of play, as shown in the systemillustrated, also permits the physician to move the coupler segmentswith respect to each other and thereby establish that proper engagementhas occurred.

Third, this system permits multiple, affirmative engagement anddisengagements of the male and female segments, i.e., multiple catheterexchanges, can be accomplished. This is yet a further advantage over theprior art coupler systems which require permanent connection of thesegments.

FIG. 3 is a sectional view of a portion of the female coupler segment 26of the present invention. FIG. 3A is an end view of the female couplersegment shown in FIG. 3. In particular, female coupler segment 26comprises a hollow tubular body 30 having a substantially circular lip16 with longitudinal slots 25 therein. Lip 16 has outside and insideedges 16′, 16″, respectively, with a radial surface 16′″ therebetween.Lip 16 can be formed by any of several techniques. However, in theembodiment shown, lip 16 was formed by coining a segment of hypotube.This technique of formation is to be contrasted with that of FIG. 2where drilling, cutting, and grinding steps were employed. It is notedthat coining lip 16 tends to create a more rounded or radiussedintersection (at 33) between tubular body 30 and lip 16 than the sameintersection (at 50) in FIG. 2. The configuration of the interiorintersection between the lip 16 and tubular body 30 will, to someextent, determine connector withdrawal forces.

Slots 25 and lip or tabs 16 define flaps 17 and 18 which move from asubstantially parallel, axial, alignment to a slightly oblique alignment(with respect to the system axis) in the coupling process. In theconnection step, radial surface 16′″ slides along the exterior surface60 of the male segment, separating the semicircular flaps 17, 18 to aslightly opened position. Tubular body 30 biases flaps 17, 18 towardeach other and tends to reduce the radial width of slot 25. When theconnection is made, flaps 17, 18 return to substantially their originalposition, a “snap” is heard or felt (or both), and the coupling processis completed. When the coupling process is complete, interior edge 16″aligns in substantially parallel fashion with shoulder 23A on maleconnector segment 15.

FIG. 4 shows in section the details of one possible approach toattaching female coupler segment 26 to elongated shaft 24. As wasdiscussed above, in a preferred embodiment, elongated shaft 24 is thedistal end of an extension wire but may also be the proximal end of aguidewire or main wire. Hollow tubular body 30 is attached to shaft 24at resistance weld or spot weld 32. As is noted above, other techniquesfor attachment may be used. In FIG. 4 the elongated shaft segmentcoupled to tubular body 30 is shown to be ramped or tapered at 34. Taper34 leads to an extension wire segment 36 which has substantially thesame outside diameter as that of hollow tubular body 30. Elongated shaft24 has been ground to a smaller diameter than wire segment 36 to enhanceflexibility. Taper 34 therefore provides a gentle transition between theextension wire body and tubular body 30 which is particularly desirable.Taper 34 permits a catheter to pass over hollow tubular body 30 (e.g.,during a catheter exchange process) without becoming caught on theconnector system structure.

FIG. 5 illustrates one possible connection structure between a guidewireproximal end 14 and a male coupler segment 15. The particular guidewirestructure employed is that of a core wire 70 having oppositely woundmultifilar coils 72, 72′ disposed therearound. Core wire 70 has areduced diameter proximal segment 74 which connects to core wire mainsection 76 through taper 78. Coils 72, 72′ and reduced diameter proximalsegment 74 are attached to male coupler segment 15, e.g., by brazing, at80 and 82, respectively. Male coupler segment 15 is brazed to guidewireproximal end 82 at bore 84 which is drilled or machined in the followingend 21 of male coupler segment 15. It is important that there be asmooth transition from male coupler segment 15 to the remainingstructure of the guidewire so that a catheter can slide smoothlythereover during an exchange process.

FIG. 6 illustrates another embodiment of the invention wherein groove23′ comprises a shoulder 23A′, a portion of reduced diameter segment 74indicated at 23B′ and the proximal end of coils 72, 72′indicated at23C′. There are many possible ways to construct a groove which willcooperate with a connecting female segment in accordance with thisinvention.

FIGS. 7, 8, 9, and 11 illustrate variations in construction of a maleconnecting segment of this invention. The variations illustrated arealternative ways in which the desired external configuration of the malecoupler segment can be created. In each of the systems illustrated, areduced diameter proximal guidewire segment 90, 91, 92, 93,respectively, is attached (at 94, 95, 96, and 97, respectively), toelongate male connector segment 98, 99, 100, and 101 respectively. Ineach instance a groove 102, 103, 104, and 105 is created or defined.FIG. 7 illustrates a coined sleeve that is attached to the wire core 90by application of glue, solder, or braze through opening 97 on theinsertion end of the segment 98. This procedure keeps annular shoulder150 clean. FIG. 8 illustrates a plasma ball weld 95 utilized on theinsertion end of male connector segment 99.

FIGS. 8, 8A and 8B illustrate different sized guidewires in which thepresent invention has been used. For example, the guidewire shown inFIG. 8 would be the structure of a 0.035 in. and 0.038 in. diameterguidewire having two counterwound spring coils 72, 72′. The embodimentof FIG. 8A has a single spring coil 72 and would be structure employedin a 0.025 in. diameter guidewire.

FIG. 8B is a structure useable for very small diameter, e.g., 0.014 in.,guidewires. No spring coils are used. The extreme proximal end of theguidewire is ground to a lesser diameter and groove 103″ is defined byelongate male connector segment 99, a reduced diameter segment 152, andtaper 154.

FIG. 9 shows a sleeve which was crimped (at 96) on the guidewire bodycore 92.

FIG. 11 illustrates an embodiment where the requisite externalconfiguration of the male segment is externally formed into a segment ofhypotube 160. Hypotube 160 then is brazed onto the proximal end of theguidewire and a rounded tip 120 is created on the remaining end.

FIG. 10 illustrates an embodiment of the invention wherein the maleconnector segment external configuration 15 is simply machined into theproximal section of the guidewire, e.g., by centerless grinding. Aradial groove or notch 110 defined by surfaces 112, 114, and 116cooperates with the lip portion of the female coupler segment.

FIG. 12 is a sectional view of an alternative embodiment of a femalecoupler segment 120 of this invention. In FIG. 12 a section of hypotube122 has a metal ring 124 brazed, soldered or glued (at 123) to its openend. Metal ring 124 has a diameter which is slightly less than theinside diameter of the hypotube 122 and thereby creates a lesserdiameter lip 126. As shown, this approach produces a substantiallycircular lip. Hypotube section 122 then is resistance welded, glued,soldered or brazed to the guidewire or extension wire core (at 128) withwhich it is associated. Electrical discharge machining or other knownfabrication techniques then are used to create lateral slot 130.Alternatively, ring 124 could be fitted inside of hypotube segment 122to create an inwardly disposed “lip” as is discussed above. Regardlessof the location of the lip, as long as the female and male segmentsoverlap sufficiently, kinking at the connection will be reduced.

In FIGS. 13 and 14 there is shown a further embodiment 200 of thecoupler system of the present invention. The embodiment shown isparticularly useful for smaller diameter, e.g., cardiovasculardimensioned, guidewires/extension wires. Generally speaking, devices towhich this embodiment of the invention may be applied will have outsidediameters in the range of about 0.010 inches to about 0.020 inches.

In FIG. 13 system 200 comprises a male coupler segment 202 and a hollowfemale coupler segment 204. Arrow 201 shows the direction of insertionof the coupler segments. Male coupler segment 202 has a first diameterproximal segment 206, leading to a first tapered segment 208 and in turnto a second, smaller diameter segment 210. Distally attached to seconddiameter segment 210 is a bullet-shaped head 212. Head 212 has a leadingor insertion end 214 and a following end 216. Insertion end 214 is of ahemispherical, rounded configuration to reduce insertion force.Following end 216 comprises an annular shoulder 218. In conjunction withsecond diameter segment 210 and taper 208, the exterior surface of malecoupler 202 defines an elongate groove or attachment zone which fitsinto female coupler segment 204.

Female coupler segment 204 comprises, in this embodiment, a section ofhypotube. In hypotube segment 204 there has been created or fabricated areduced diameter segment 220. The interior diameter of hypotube segment204 (not shown in FIG. 13) is proportionately reduced. For example,segment 220 may be a radial bead or dent rolled into the hypotubesegment 204 so as to create a reduced interior diameter region.Intersecting bead 220 is a single lateral slot 222. Slot 222 has beencut entirely through hypotube segment 204 from the outside to the insideso as to provide room for bead 220 to expand radially when male segment202 is inserted into female segment 204. Slot 222 has generally parallelsides 223, 225 and symmetric, radiussed ends 227, 229. Especially forsmaller diameter coupler systems, a single lateral slot intersectingbead 220 is preferred. Female coupler segment 204 is, in turn, attachedto one or the other of the guidewire or the extension wire 221 at braze224. As is shown, the outside diameter of coupler segment 204 issubstantially the same as that of the guidewire or extension wire 221 towhich it was attached. Thus, ease of catheter use is provided in that acatheter slides over the coupler system without becoming caught at thecoupler segment-guidewire/extension wire intersection.

FIG. 14 shows the interior details of the system of FIG. 13 in partialsection. With male coupler segment 202 inserted into female segment 204,annular shoulder 218, second diameter segment 210 and taper 208cooperate with reduced diameter segment or bead 220 to create a coupledsystem. Female coupler segment wall (shown in section and indicatedgenerally at 205) defines those structures. As is shown, an abruptlytapered section 226 and a reduced diameter section 228 (reduced from thediameter of the main section of the guidewire/extension wire 231) areformed on the guidewire/extension wire end 231 to which female couplersegment 204 is attached at braze 224. Further, taper 208 is shown tocooperate with hypotube open end 230 to restrict or control the extentto which the male segment may be inserted into the female segment. Last,a tactile “snap” (and accompanying sound) will be heard as annularshoulder 218 passes through the reduced interior diameter segment 219defined by bead 220, and the bead 220 abruptly returns or snaps to itsoriginal uncompressed diameter.

Insertion and withdrawal forces are always of concern with connectorsystems of vascular (especially cardiovascular) dimension and arecontrollable in the practice of this aspect of the invention.Hemispherical bullet-shaped head 212 reduces the forces necessary tocouple the male and female segments. The relationship between annularshoulder 218 and the cross-sectional configuration of bead 220 willdetermine the magnitude of force required to decouple the segments.Generally speaking, the configuration shown in FIG. 14, i.e., a beadhaving a lesser diameter following edge (at 230) and a larger diameterleading edge (at 232) will substantially increase withdrawal forces. Theangular relationship between annular shoulder 218 and the following edge230 (among other factors) also will determine the magnitude ofwithdrawal forces.

In light of the above disclosure, one skilled in this art willunderstand that several techniques may be used to create the inventivestructure disclosed. Specifically, bead 220 can be rolled (i.e.,roll-formed) into hypotube segment 204. Slot 222 may then be machined orotherwise cut, e.g., via laser, into, through bead 220, to complete thisfeature of the invention. The male segment can be created by, e.g.,centerless grinding, of the end portion of the guidewire/extension wireon which it is located.

The main guidewire section 11 is intended for use in positioning acatheter (not shown) in the vasculature of a patient, and it has alength corresponding to the length of a conventional guidewire for thispurpose. Details of typical catheters and guidewires can be found inU.S. Pat. No. 4,538,622 (Samson et al.) and U.S. Pat. No. 4,569,347(Frisbie). Those patents are incorporated by reference herein in theirentirety.

Extension wire 12 is sufficiently long so that when the main guidewiresection 11 and extension wire 12 are connected together, the guidewiresystem or exchange wire 10 has an overall length suitable for catheterexchange without removing the main guidewire 11 from the patient'svascular system. With a catheter having a length on the order of about65 cm to 175 cm, for example, guidewire 11 would have a length of about100 to about 200 cm, and extension wire 12 would have a length of about100 to about 200 cm (or longer).

Shafts 13 and 24 and female segment 26 can be fabricated fromessentially any suitable material, such as stainless steel, Elgiloy, orthe shape memory alloy referred to as Nitinol (55% Ni-Bal. Ti). Eachshould have an overall largest diameter which allows, e.g., a dilatationcatheter, to pass freely thereover. Preferably, the two shafts 13 and 24are provided with a smooth transition between them. Either or both ofshafts 13, 24 can be provided with a coating of polymers or elastomerssuch as PEBAX polyamide, polyurethane, polytetrafluoroethylene (PTFE),or other such material well known to one skilled in this art.

Typical dimensions of the main guidewire section include an outsidediameter of the shaft 13 of about 0.009 to about 0.065 inch, an outsidediameter of the male insertion segment about 0.006 inch to about 0.050inch and a length of about 0.025 to about 0.250 inch. The femaleconnector segment has dimensions which generally cooperate with the malesegment dimensions and a length of about 0.060 inches to about 1.0inches and an outside diameter of about 0.009 in. to about 0.065 in.While this invention is particularly applicable to larger diameterguidewires, e.g., 0.038 inches and 0.035 inches, smaller diameterapplications, e.g., 0.025 inches or less, down to 0.009 inch diameterwires, are also within its scope. Generally speaking, the ratio of malesegment outside diameter to male segment length and female segmentinside diameter to female segment length will fall in the range of 1:100to about 1:1.Having a segment length which is larger than the respectivesegment diameter tends to keep the wires more axially aligned, therebyminimizing unwanted bending and kinking.

Percutaneous transluminal angioplasty is a medical procedure in whichthe present invention can be used. In use, the main guidewire section 11is percutaneously introduced into the vascular system of a patient witha dilatation catheter through the skin by means of an introducer (notshown). The distal tip of the guidewire is advanced beyond the distaltip of the dilatation catheter while the latter is held in place. Themain guidewire section 11 is advanced into the selected vessel. Theguidewire tip is preferably advanced through the lesion and beyond it,in order to permit the balloon portion of the dilatation catheter to bepositioned within the lesion over a more supportive section of theguidewire. Once in position, the main guidewire section 11 is held inplace and the dilatation catheter is advanced along it until theinflatable balloon thereof is within the lesion. Male connector segment15 remains outside the patient's body and outside any adapter which maybe connected to the proximal end of the dilatation catheter. Ifnecessary, e.g., to retain a sufficient length of the main guidewiresection 11 outside the catheter for the physician to grip, the guidewireand catheter may be advanced together substantially in unison.

To exchange catheters, the main guidewire section 11 is extended bymanually snapping the female tubular member 26 onto the male member 15.When the two guidewire sections are engaged, the dilatation catheter canthen be withdrawn from the patient's body over the extended guidewiresystem.

A new dilatation catheter may then be introduced over the extensionsection 12 and advanced along the main guidewire section 11 within thepatient's body until the balloon crosses the lesion. Once the proximalend of the new catheter has advanced beyond the connection betweenfemale member 26 and male member 15, section 12 can be removed fromsection 11 by unsnapping the female member 26 by pulling the twosections apart. This can be accomplished without disturbing the positionof the main section 11 in the patient's body.

The above description describes utilization of the present inventionprimarily in coronary angioplasty catheter exchange. It is to beunderstood that this invention has application in essentially anyprocedure where a catheter is utilized for diagnostic or interventionalapplications.

This invention has a number of important features and advantages. Thetwo sections of the guidewire can be connected together whenever alonger, exchange wire is needed, and they can be disconnected wheneverthe additional length is not required. The two sections of the guidewiremay be connected and disconnected (and reconnected, if desired) by thephysician by simply “snapping” and “unsnapping” the male segment into orout of the female segment. Subsequent to engagement, the segments can befreely rotated with respect to each other (e.g., to permit the guidewireto be steered) and can easily be disengaged. This can be done as needed,and no special tools are required whether to make the connection or toseparate it. Thus, catheter exchange is greatly simplified. This alsopermits the same guidewire to be repositioned to second and multipleadditional vascular sites which then may be treated with differentcatheters, making the present system very versatile.

As noted in the previous paragraph, a guidewire extension system of thisinvention can be multiply engaged and disengaged. The present inventiontherefore permits two or more catheter exchanges, during a medicalprocedure, without a need to reposition or exchange the main orguidewire. Generally speaking, the ease of disengagement (i.e., thepounds of force needed to disengage an extension wire from a guide wire)has been found to be in the range of about 0.2 to about 5.0 lbs.,preferably about 0.3to about 3.0 lbs., and most preferably about 0.7lbs. to about 2.0 lbs. Factors which affect withdrawal forces includethe overall device diameter (withdrawal forces being higher for largerdiameter devices), wall thickness of the tube, slot configurations, thematerials of which the male and female coupler segments are made, andthe relationship between the cooperating surfaces on the male and femalecoupler segments. The more abrupt or acute the relationship, the higherthe withdrawal forces. With reference to FIG. 2, the more nearlyperpendicularly (relative to the axis of the device) shoulder 23Aengages surface 46, the more difficult withdrawal of male couplersegment from the female coupler segment.

It is apparent from the foregoing that a new and improved extendedguidewire system has been provided. While the present invention has beendescribed herein with the male connecting element fixed to the distalend of the main guidewire, and the female member located on the distalend of the extension section, it is obvious that the female connectormember and male connector member may be interchanged. Moreover, it willbe apparent to those familiar with the art that other modifications andimprovements can be made without departing from the scope of theinvention as defined by the following claims.

What is claimed is as follows:
 1. A coupler for a guide wire/extensionwire system, the coupler comprising; a male segment and a femalesegment, wherein the male and female segments are designed to cooperateto couple and decouple a guidewire to an extension wire, each beingattached to one or the other of the distal end of the extension wire orthe proximal end of the guidewire; the female segment comprising: ahollow, elongate sleeve, the sleeve having opposite ends and a sleevewall which defines inside and outside sleeve diameters, one of saidopposite ends of the sleeve having an inside diameter such that it canbe firmly attached to the guidewire or the extension wire, there beingdisposed between said ends and being defined by the inside surface ofsaid sleeve wall, a reduced interior diameter zone, the zone havingpassing therethrough a longitudinally extending slot, the slot beingdefined by said sleeve wall and passing through said wall; the malesegment comprising: an elongate member, the elongate member having anexterior surface which defines an outside diameter which is less thansaid sleeve wall inside diameter, and oppositely disposed insertion andfollowing ends, the exterior surface of said elongate member defining agroove and an annular shoulder on said following end, said groove havinga diameter which cooperates with the reduced interior diameter zonedefined by the sleeve wall of the female member so that when said malesegment is inserted into said female segment, said female couplersegment is rotatively retained along said male coupler segment with anannular space therebetween, and coupling occurs with a tactileindication that insertion is complete.
 2. A coupler according to claim 1wherein the outside diameter of the elongate member defined by itsexterior surface is less than the inside diameter of the female coupler,leaving an annular space therebetween.
 3. A coupler according to claim 1wherein the tactile indication of a “snap” is experienced when thefemale segment and male member are completely intercoupled.
 4. A coupleraccording to claim 1 wherein the male member has a tapered insertionend, the taper permitting easy insertion of said male member into saidfemale coupler.
 5. A coupler according to claim 1 wherein the femalesegment is disposed on the distal end of the extension wire and the malemember is disposed on the proximal end of the guidewire.
 6. A coupleraccording to claim 1 wherein the guidewire comprises a steerableguidewire having a core wire and a helical coil disposed about itsdistal end.
 7. A coupler according to claim 1 wherein the reduceddiameter zone is a bead, the slot being disposed substantiallyperpendicular thereto.
 8. A coupler for a guidewire/extension wiresystem, the coupler comprising: a male segment and a female segment,wherein the male and female segments cooperate to couple and decouple aguidewire to an extension wire when the male segment is disposed on theproximal end of the guidewire, and the cooperaung female segment isdisposed on the distal end of the extension wire, the female segmentcomprising: a hollow, elongate sleeve, the sleeve having opposite endsand a sleeve wall which defines inside and outside sleeve diameters, oneof said ends being attached to said extension wire, there being disposedbetween said ends, a reduced interior diameter zone, that zone havingpassing therethrough, a longitudinally extending slot, the slot beingdefined by said sleeve wall and passing through said wall; the malesegment comprising: an elongate member, the elongate member having anexterior surface which defines an outside diameter which is less thansaid sleeve inside diameter, and opposite leading and following ends,the exterior surface of said member defining a radial groove and anannular shoulder on said following end, said radial groove having adiameter which cooperates with said reduced diameter zone so that aftersaid male segment is inserted into said female segment is rotativelycoupled thereto; and said male segment is retained within said femalesegment which an annular space therebetween, and coupling occurs with atactile indication that insertion is complete.
 9. A coupler according toclaim 8 wherein the reduced diameter zone is a bead.
 10. A coupleraccording to claim 8 wherein the outside diameter of the male member asdefined by its exterior surface is less than the inside diameter of thefemale coupler, leaving an annular space therebetween.
 11. A coupleraccording to claim 8 wherein the tactile sensation of a “snap” isexperienced when the female segment and male member are completelyintercoupled.
 12. A coupler according to claim 8 wherein the male memberhas a tapered leading end, the taper permitting easy insertion of saidmale member into said female coupler.
 13. A coupler according to claim 8wherein the guidewire comprises a steerable guidewire having a pluralityof multifilar, oppositely wound coils disposed about its distal end. 14.A method of coupling a main wire and an extension wire, one or the otherof said main wire or said extension wire having a hollow, cylindricalfemale coupler segment, the other of said main wire or said extensionwire having an elongate male segment, the method including the steps of:providing a main wire having a coupler segment on the proximal endthereof, the coupler segment comprising a hollow, cylindrical femalecoupler segment or an elongate male coupler segment; providing anextension wire having a coupler segment on its distal end, the couplersegment comprising a hollow cylindrical female coupler segment or anelongate male coupler segment; coupling the main wire and the extensionwire by inserting the male coupler into the female coupler until atactile sensation indicates coupling has been completed, the couplersegments being rotatable with respect to each other and defining anannular space therebetween; and withdrawing the male segment from thefemale segment to decouple the main wire from the extension wire.
 15. Amethod according to claim 14, wherein the decoupling step isaccomplished by application of a decoupling force in the range of about0.2 pounds to about 5 pounds.
 16. A method according to claim 14 whereinthe decoupling step is accomplished by application of a decoupling forcein the range of about 0.3 to 3.0 pounds.
 17. A coupler for aguidewire/extension wire system, the coupler comprising: a male segmentand a female segment, wherein the male and female segments cooperate tocouple and decouple a guidewire to an extension wire when the male andfemale segments are each attached to one or the other of the distal endof the extension wire or the proximal end of the guidewire, the femalesegment comprising: a hollow, elongate sleeve, the sleeve havingopposite ends and a sleeve wall which defines inside and outside sleevediameters, one of said ends having an inside diameter such that it canbe attached to one of said guidewire or said extension wire, there beingdisposed between said ends and being defined by said sleeve wall, areduced interior diameter zone, the zone having passing therethrough,one or more longitudinally extending slots, being defined by said sleevewall and passing through said wall, the male segment comprising: anelongate member, the member having an exterior surface, and oppositelydisposed insertion and following ends, the exterior surface of saidmember defining a groove and an annular shoulder on said following end,said groove having a diameter which cooperates with said reducedinterior diameter zone so that when said male segment is inserted intosaid female segment, said female coupler segment is retained along saidmale coupler segment and is rotatively coupled thereto, coupling occurswith a tactile indication that insertion is complete decoupling occursby application of withdrawal forces in the range of about 0.2 to about5.0 pounds, whereby said male segment and said female segments areconveniently coupled and decoupled.
 18. A coupler according to claim 17wherein the outside diameter of the elongate member defined by itsexterior surface is less than the inside diameter of the female coupler,leaving an annular space therebetween.
 19. A coupler according to claim17 wherein the tactile indication of a “snap” is experienced when thefemale segment and male member are completely intercoupled.